<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .box{
            width: 500px;
            height: 500px;
            border: 2px solid black;
            margin: 100px auto;
            display: flex;
            /* justify-content: flex-start; */
            /* justify-content: flex-end; */
            /* justify-content: center; */
            /* justify-content:space-between */
            /* justify-content:space-around; */
            /* 
            调整主轴
            flex-start      正向对齐
            flex-end        反向对齐
            center          中心对齐
            space-between   两端对齐
            space-around    距离环绕（等比对齐）
            */
            
            align-items: center;
            /* 
            调整侧轴
            flex-start
            flex-end
            center
            */
        }
        .box span{
            width: 100px;
            height: 100px;
            border: 1px dashed red;
        } 
    </style>
</head>
<body>
    <div class="box">
        <span>1111</span>
        <span>2222</span>
        <span>3333</span>
        <span>4444</span>
    </div>
</body>
</html>